Star names in short supply in men's Olympic football tournament
As captain of France and the most famous athlete in the country hosting this year's Games, Mbappe's presence in coach Thierry Henry's Olympic squad would have been an enormous boost for organisers as well as for the team's chances of winning gold.
But Mbappe, 25, had to accept that his new club Real Madrid would not allow him to participate immediately after he played in the French side that reached the semi-finals of Euro 2024 in Germany.
That is the problem for the men's football competition, which begins on Wednesday and runs until August 9.
Clubs are not obliged to release players for a tournament held outside an official FIFA window for international football, following straight on from the European Championship and Copa America.
Messi, now 37 and part of the Argentina team that claimed Olympic gold in Beijing in 2008, ruled himself out of Javier Mascherano's squad for Paris shortly before the Copa America in the United States, which his country won.
"I spoke with Mascherano, and we immediately agreed on the situation," Messi told ESPN.
"At my age, I don't want to play everything and I need to make the right choices."
Henry, a French footballing great, also missed out on several other players he had hoped to call up.
"The last time I had so many rejections was when I was at high school," he joked when announcing a team in which the most recognisable names are Alexandre Lacazette, the 33-year-old Lyon striker, and new Bayern Munich signing Michael Olise.
The competition is restricted to players aged under 23, apart from a maximum of three overage players per squad.
As well as the superstar names, the tournament is also missing Brazil, who won gold in Rio de Janeiro in 2016 and retained the title in Tokyo three years ago, beating Spain in the final.
Argentina and Spain contenders
They failed to qualify, but Argentina must fancy their chances of ensuring a sixth straight Latin American winner of the men's football gold medal.
"Obviously our objective is to try to compete and go all the way, and I think we will have a team that can do that," coach Mascherano, who won as a player in 2004 and 2008, said in an interview with South American confederation CONMEBOL.
In Julian Alvarez, the Manchester City striker who won the 2022 World Cup and the recent Copa America, they will have one of the highest-profile players taking part.
Argentina are in Group B with Iraq, Ukraine and a Morocco side who have secured the services of Paris Saint-Germain right-back Achraf Hakimi.
France kick off their campaign against the United States before also playing Guinea and New Zealand in Group A.
Winners in 1992 and silver medallists in Tokyo, Spain are targeting gold after their triumph at Euro 2024.
Luis de la Fuente, coach of Spain's Euros-winning side, led the team to the final at the last Olympics. Santi Denia, his assistant three years ago, is in charge now.
Leading names from the European Championship such as Lamine Yamal are not involved, but another prodigious young Barcelona talent will feature, 17-year-old centre-back Pau Cubarsi.
"He is really proud to be getting the experience of the Olympics. You never know if you will get another chance, even being so young," Denia told Marca of Cubarsi.
Spain are in Group C with Uzbekistan, the Dominican Republic and Egypt, who did not secure the services of Liverpool's Mohamed Salah.
Asian Under-23 champions Japan - who named a squad without overage players - are in Group D alongside Paraguay, Mali and Israel.
Matches will not only be played in Paris, with Nantes, Bordeaux, Nice and Saint-Etienne all hosting games.
The semi-finals will be in Lyon and Marseille, while Paris's Parc des Princes hosts the final.